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Old Jan 05, 2007, 05:51 PM
Watch out for that TREE!
Houston, Tx
Joined Oct 2006
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Torque roll

I've been flying my estarter with a GWS 9050HD prop, and today I stuck a 8060HD on it. Seems with the 9050 I was always having to correct for straight/level flight. Change in throttle position would throw the trim off, a lot if throttle changed a lot. This didn't seem to be a problem with the 8060, flew straight and level no matter what throttle position was set. Is this torque roll? Or was I just imaging it along with the pink elephants and purple gophers.

John
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Old Jan 05, 2007, 06:34 PM
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Livermore, CA
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Sounds like it to me. My GWS 109 would fly nice and stright with the stock motor. Since I got one with a Axi outrunner and bigger prop, I cant launch it full power, without it wanting to roll into the ground!
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Old Jan 05, 2007, 07:41 PM
Ascended Master
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Palmdale, CA
Joined Oct 2000
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The Estarter is rudder -elevator?
Changes in thrust will have effects on the directional trim.
And changes in lateral trim are more likely to be the result of wing warps than torque on these low powered planes.
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Old Jan 05, 2007, 07:58 PM
Watch out for that TREE!
Houston, Tx
Joined Oct 2006
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SP, it is full 4 channel with a skatty 400xt, 1250 3s lipo.

John
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Old Jan 06, 2007, 02:51 AM
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Christchurch, New Zealand
Joined Jun 2006
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It's torque roll, you're not imagining it. Fullsize planes do it too, and so will the smaller prop, it's just lessened it enough so you don't notice anymore. If you have a computer radio you can make it go away with a bit of throttle to rudder mix.
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Old Jan 06, 2007, 08:01 AM
Texas Buzzard
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McAllen,Texas
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If any of you have flown full-sized planes with a tailwheel ( Aeronca Champion, etc.) you noticed that beginning the take off roll as you applied throttle the nose would swing to the LEFT. We apply a bit of Right rudder to maintain a straight path down the runway. THAT WAS TORQUE that swung the nose to the left. From the pilots position the prop was turning clockwise ( a right handed prop.).

With overpowered glow RC planes when making a slow approach and the Jamming the throttle to full power suddenly, the plane will roll to it's left, sometimes even do a diving Left turn....a no,no. Apply throttle smoothly and be ready to give a tiny bit of right rudder and some right aileron to compensate....smooth application of throttle is a good practice.

Newton's Third Law: For every force applied, there will be an equal but opposite force. Or something like that! **** The right hand prop is forcing the air to move ( that's it's job !!). The prop is moving clockwise. The prop is resisted by the air. The air pushes back against the prop. Since the prop is attached to the plane throught the shaft..... the prop is forcing the shaft to rotate in a counterclockwise direction. ** So the entire plane is forced to roll left by a right-handed prop. Use a tad of right rudder!!
Lots of "old-timers" used 2 to 3 degrees of RIGHT THRUST to compensate for TORQUE. It is standard practice on low speed aircraft. Try right thrust- you might like it!!!

WARPS: A small warp in a wing or a misaligned tail surface will be quite noticable at higher speeds. The effect of a warp may not show up at low speeds.
Lets say our WW II Thunderbolt's left wing has a warp so that the trailing edge is warped down ( it has some positive incidence). At high speed with controls at neutral this plane will have a tendency to have a Right Roll. But at landing speed it's rolling tendency will not show up as much.
The Moral of the Story IS Warps Are BADD. Take a few minutes more to build straight and check for warps 2 times then check one more time. Remove them!
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Last edited by Texas Buzzard; Jan 06, 2007 at 08:11 AM.
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Old Jan 06, 2007, 10:09 AM
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Frederick Maryland USA
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Although what you noticed is often commonly called torque roll there are actually alot of different forces at play. As explained in Scott Stoops' "Mastering Radio Controlled Flight" the yaw to the left is called P-factor. This yaw occurs when the angle of the nose is changed and is due to differences in thrust produced by the propellor's blades when their angles of attack change moving upward or downward in their rotation. With the standard direction of rotation, when the nose point up the yaw is to the left and when the nose points down the yaw is to the right. This can be conteracted using the rudder.
There is also an effect of uneven airflow (spiral airstream) that tends to push more on one side of the rudder also causing a yaw to the left. This effect can be countered by a few of degrees of angle in the motor mount.
As you have noticed, these effects (along with gyroscopic precession) are reduced with a smaller prop diameter.
Torque is a seperate beastie and will instead roll (not yaw) the plane and has to be handled by careful application of the throttle on take off or any time the airspeed gets too low to provide good control authority.
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Old Jan 06, 2007, 10:14 AM
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gastonmc@sbcglo

Well put.I think that will help alot of people.
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Old Jan 06, 2007, 10:39 AM
Texas Buzzard
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Duetto, oh yes - the "p" factor. All that you posted was correct. You are quite knowledgeable.
But since this thread seemed to be for the beginner, er...ah, wanted to keep it as simple as possible , yet give enough info to be useful.
Right motor/engine thrust and an application of right rudder + a judicious ( gentle) increase in the throttle setting just might save a rebuilding job for someone.
#1 Check for Warps, #2. Advance throttle gently, #3 Be ready to apply a bit of right rudder and or right aileron when acceleration from low speed.
Did you ever see a video of a WW II prop job making a take off from a carrier w/o the use of a catapult? You will see a generous use of Right Rudder! It is real not imagined. Thanks Duetto for completing this concept. The "p' factor is easily seen in a high-powered Free Flight as it accelerates. The swirlng airstream hits the pylon and forces a roll. Assume a free flight with a pylon (ala Playboy)
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Old Jan 06, 2007, 11:01 AM
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Frederick Maryland USA
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I didn't want to complicate things unduely either but with relatively cheap brushless motors available many beginners are flying quite powerful planes. Having "torque rolled" a couple of my planes on take off before educating my left thumb, I didn't want anyone to think that it was always enough to simply counter with a bit of trim or rudder application without taking the throttle into account.
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Old Jan 06, 2007, 11:28 AM
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P-factor problems are more often encountered with models than "torque rolls" because we abuse the takeoff speed... taking off too slowly, at high angles, or throw too steeply when hand launching.
With proper technique, such effects go away.
For the ultimate "torque roll", one of our test pilots had flown the Grumman F8F Bearcat in the Navy. He said they delighted to take it straight up, pull back on the power until it lost forward speed, and cram on full power... it would torque roll for real!
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Old Jan 06, 2007, 11:50 AM
Watch out for that TREE!
Houston, Tx
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Wow, ask for a crumb and get a whole loaf. Thanks guys, for the info. The effect seemed to be most noticable when jamming throttle full for aerobatics (at least what I call aerobatics), nose would pull up and roll out. Nice to know why.

Thanks again,
John
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Old Jan 06, 2007, 12:16 PM
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I think true torque roll is what you experience when you turn on an electric drill and it wants to roll left. A drill rotates the same way as the prop on a plane, and the torque produced while it's either accelerating, or counteracting an applied force, acts to spin it in the opposite direction.

I'm not a physicist though, and it's really only a thought I had. I could be way off.

Chuck
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Old Jan 06, 2007, 09:43 PM
oh crap! did I do that?
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cochran,GA
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GD I have the exact same setup as you and I too have experienced this mainly when taking off at full speed. I have mine trimmed to fly level at about 1/2 to 2/3 throttle so that I have some power left to get out of trouble if I need it. I usally fly a few mistakes high as I have found that this plane likes to tip stall at low speed aileron induced turns.
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Old Jan 07, 2007, 10:46 AM
Watch out for that TREE!
Houston, Tx
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Quote:
Originally Posted by JTStone
GD I have the exact same setup as you and I too have experienced this mainly when taking off at full speed. I have mine trimmed to fly level at about 1/2 to 2/3 throttle so that I have some power left to get out of trouble if I need it. I usally fly a few mistakes high as I have found that this plane likes to tip stall at low speed aileron induced turns.

JT, I also, have noticed the tip stall. I thought it was all the epoxy in the nose & tail dragging it down. I am kind of surprised after reading how docile a plane the estarter is. I guess thats what happens when you ASSUME to much. Gotta stop taking things for granted, so far I have been lucky that it hasn't bit me harder in the butt, but the SS taught me so many bad habits. That thing will fly no matter how it is setup, I think.
Engage brain, then think, TWICE, before you do.

John
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